so, I'm sitting there happily playing FFXI last night, halfway through typing a sentence to someone... and boom, lights off, complete instant hard crash.. computer turned itself back on about 3 seconds later (i didnt touch it, i was still staring blankly at the keyboard in a stupor)... fans turned on, cdrom's powered, etc... no keyboard lights at all, no video, no POST... pulled the RAM, disconnected all the IDE's, reseated the vidcard. then later removed the vidcard (no PCI cards in the machine), swapped out the PSU, nothing... only odd thing is, if I would leave the machine turned off for about 5-15 minutes, but it was still plugged in, it would randomly turn itself on and give a weird long/long/never-ending beep code..
I have a spare CPU that I guess I'll try next, since I may as well... pretty sure its the motherboard itself though, as I actually *burnt* my fingertips on the little black chips (part of the Voltage Regulator, their tech name escapes me) and capacitors near the CPU... and I can't recall them *ever* being hot before... actually had to ice them, and still ended up with a blister on one finger (i had to touch it 3 times to make sure I wasnt imagining things... I never claimed to be swift ;)